Spark plug



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May 16, 1939- A. N. COOPER SPARK PLUG Filed Juiy e, 1958 Z MW@ 4 www 6. M7/75 56,1 75 l .mmm www? lgg .u \\.`,mm 0 w w m W f M M w. ad

Patented May 16, 1939 UNITED STATES PATENT OFFICE SPARK PLUG Application July 6, 1938, Serial No. 217,758

5 Claims.

This invention relates to spark plugs and one of the objects is to provide a plug having separable porcelains provided with a connecting shell through which the electrodes of an intensifier can be seen so that it can be determined readily whether or not the spark plug is functioning.

A further object is to provide a spark plug the outer section of which can be removed readily without danger of breaking either of the porcelain members.

With the foregoing and other objects in View which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter 15 more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

20 In the accompanying drawing the preferred form of the invention has been shown.

In said drawing:

Figure 1 is a front elevation of the spark plug.

Figure 2 is a section taken longitudinally there- 25 through.

Figure 3 is a section on line 3 3, Figure 1.

Figure 4 is an enlarged transverse section through a portion of the spark plug and showing the metal-covered asbestos gasket used in con- SU nection with one of the porcelains.

Referring to the figures by characters of reference I designates the screw-threaded base or body portion of the plug which is exteriorly screwthreaded as at 2 so as to be inserted into the opening provided therefor. This plug has an enlarged upper portion 3 which is angular so as to form a nut-like portion which can be gripped and held by a wrench.

This body portion of the plug is formed with a 4o bore 4 at its lower end and a counterbore 5 at its upper end, there being an inclined shoulder 6 at the base of the counterbore while the outer end of the counterbore is screw-threaded as at 1. A porcelain 8 is adapted to be fitted in the coun- .,ff, terbore, this porcelain having a tapered end portion 9 extending through the lower bore 4 and projecting therebeyond while the upper portion of the porcelain is cylindrical, as indicated at I0 and is spaced from and projects outwardly from t.; the counterbore at the threaded end thereof. 'I'he intermediate portion II of the porcelain is tted snugly within the inner portion of the counterbore and has upper and lower tapered annular shoulders I2 and I3 respectively, shoulder I3 bearing upon a gasket I4 located on shoulder B, as

(Cl. 12B- 169) indicated in the drawing while another gasket' I5 is mounted on the upper shoulder I2 of the porcelain and is adapted to be engaged and compressed by a tubular nut I screwed into the upper end of the counterbore. This nut projects outwardly il from the counterbore and has a tapered head I'I at the base of which is an annular groove I8. The upper wall of this groove is extended at right angles to the longitudinal axis of the nut so as to form a retaining shoulder I9 as shown parl0 ticularly in Figure 4.

Obviously when the nut I6 is tightened within the counterbore it will place the two gaskets I4 and I under compression so that the porcelain will be held securely to the body portion of the 15 plug Without being injured. It is preferred to make each gasket out of asbestos covered with copper, the asbestos being indicated at in Figure 4 while the copper covering is indicated at 2 I.

The other porcelain of the spark plug has been 20 indicated at 22 and has a tapered lower end portion 23 provided with an annular groove 24.

An electrode 25 is secured within and extends longitudinally of the porcelain II at the center thereof and projects at its end from the porce- 25 lain. Another electrode 25 is secured within the porcelain 22 and is formed with or connected to a threaded stem 2l which projects upwardly from porcelain 22 where it can be engaged by a washer 28 and a binding nut 25. Electrode 26 projects downwardly from the porcelain 22 and is adapted to be extended close to and in alinement with the adjacent end of the electrode 25. The two electrodes are held detachably in these relative positions by a shell 30 formed of brass or any 35 other suitable material with a frusto-conical upper end 3l and an inturned lower end 32. Slots 33 are formed within the upper end of the shell and extend downwardly toward the points adjacent to the center or" the shell while additional slots 3d are extended upwardly from the lower end of the shell. In addition to these openings the shell is provided with one or more sight openings 35 located where the ends of the electrodes 25 and 26 can be seen within the-shell. 45

The open ends of the shell are so proportioned that, when the lower end is forced against the tapered head I7 of nut l, it will be expanded until the inturned edge portion 32 of the shell is brought opposite groove i8 whereupon it will 50 snap into the groove, as shown in Figures 2 and 4, thereby holding the shell assembled with the lower porcelain. By forcing the tapered end 23 of porcelain 22 into the upper end of the shell 30, said end will be expanded until the upper edge of the shell arrives opposite the groove 24 whereupon said edge, which is inturned, will snap into the groove as shown, thus holding the porcelain 22 assembled with the shell and also holding the two electrodes properly positioned relative to each other. Obviously with the parts thus assembled it is possible at all times to View the electrodes within the shell to determine whether or not the spark plug is properly functioning.

The parts can be easily taken apart by exerting sufficient pressure against the shell to force it off of nut I6 and off of the porcelain 22.

By connecting the parts in the manner described it is a simple matter to separate them without the use of special tools and it is also a simple matter to assemble them. The parts can be held together without danger of breaking the porcelain.

The term porcelain used herein is intended to cover any suitable insulator constructed as described.

What is claimed is:

1. A spark plug including a threaded body portion having a bore in one end and a counterbore at the other end, there being a tapered shoulder at the inner end of the counterbore constituting a seat, an insulator seated in the bore and counterbore and having annular shoulders, an electrode extending through the insulator, a nut seated in the counterbore and cooperating with the shoulder to clamp the insulator within the body, said nut having a projecting tapered end and an annular groove adjacent to said end, a second insulator having a tapered end and an annular groove, an electrode seated therein and projecting therefrom, and a contractible and expansible shell detachably embracing the grooved nut and the grooved insulator respectively, said shell constituting means for holding the insulators fixedly spaced and the electrodes in operative relation to each other.

2. A spark plug including spaced insulators, electrodes carried thereby, a body portion, means for fastening one of the insulators to the body portion, said means including a tapered head having an annular groove at the base thereof, and a resilient shell embracing said means and the insulators and constituting means for holding the insulators and the electrodes assembled in operative relation, there being an opening in the shell through which the electrodes are visible between the insulators.

3. A spark plug including spaced insulators, electrodes therein, a body portion, means for securing one of the insulators to the body portion, said means including a tapered head having an annular groove at the base thereof, there being an annular groove in the other insulator, and a resilient shell detachably engaging the grooved insulator and said grooved holding means, said shell including inturned ends seated within the respective grooves, said ends being slotted longitudinally of the shell.

4. A spark plug including a shell open at its ends, said ends being inturned and said shell being slotted longitudindally inwardly from its respective ends, the shell being formed of resilient material, an insulator insertable into one end of the shell and having an annular groove for the reception of one of the inturned ends, an electrode within and extending from said insulator, a second insulator, an electrode therein and extending therefrom, and means extending into the other end of the shell and grooved to receive said inturned end, for holding the insulators and their electrodes in operative relation.

5. A spark plug including a shell open at its ends, said ends being inturned and said shell being slotted longitudinally inwardly from its respective ends, the shell being formed of resilient material, an insulator insertable into one end of the shell and having an annular groove for the reception of one of the inturned ends, an electrode within and extending from said insulator, a secoind insulator, an electrode therein and extending therefrom, and means extending into the other end oi the shell and grooved to receive said inturned end, for holding the insulators and their electrodes in operative relation, said shell being expansible at its ends to release the insulators.

MARY H. COOPER. Administratri of the Estate of Albert N. Cooper,

Deceased. 

